7.
3.
 So nitro group is present in benzene ring
4.
 The benzene ring in phthalic acid
produced by oxidation of
aminonaphthalene is not the same
ring is that obtained by oxidation
of nitronaphthalene.

8.
 i.e. Naphthalene contains two benzene rings
and we can explain this by this equation

9.
The structure of naphthalene is confirmed by
method of its synthesis
Howarth method